One of them was so big — with a diameter of over 12 centimetres — that he gave it to the mayor of Whitehorse.

"The mayor told me later, 'That was the best tomato we had ever tasted and it was the biggest tomato we had ever seen,'" said Bartsch, chuckling.

Bartsch says it's all thanks to his retirement project — an all-locally produced root heater that uses the sun to warm up the soil during the frosty Yukon spring and fall.

And it's not used in a greenhouse.

Chris Bartsch's garden on June 12, 2017 (left) grows into a lush plot of crops just five weeks later, July 20, 2017 (right). (Submitted by Chris Bartsch)

"What I'm really trying to prove here is that this can be done at a reasonable cost ... but the benefits of it are huge," said 82-year-old Bartsch, who's been tinkering with the technology since last year.

How it works

Previously a radial floor heating system installer, Bartsch was inspired to find material available locally to build his root heater — or solar collector, as he calls it.

It looks like an unassuming framed, silver and black rectangle, and is made of scraps of roofing metal, black tubing (to absorb sunlight), a refurbished circulator pump, hoses, and some electricity.

The contraption, acting like a solar panel, soaks in the sunlight and heats the water that pumps into the ground. In turn, warm water circulates through hoses laid out underneath the soil, giving crops the optimal conditions of around 21 C to flourish.

The back of Bartsch's root heater which acts like a solar panel. It soaks in the sunlight and heats the water that pumps into the ground. (Submitted by Chris Bartsch)

He says now, it takes him a day and a half to make one root heater.

This kind of a "root zone heating" system isn't new — but many on the market have to be shipped from afar, and are typically generated by bulky gas boilers or fuel tanks.

"[Bartsch's plants] are still growing while other gardens are being shut down."- Agnes Seitz

"They found it was so expensive to operate it in greenhouses," said Bartsch.

Bartsch wants to show the average gardener that it can be made at home, and it doesn't have to cost much to heat it. He's planning on developing a battery-powered circulator pump for those who are off the grid.

"Eventually you'll see just how marvelous this is," he said.

'Still growing' in September

Bartsch planted a test garden at the Lorne Mt. Community Centre, just south of Whitehorse, last year.

"Five weeks later, we were eating out of that garden," he said. "So we're on to something."

"We have some of the most challenging conditions here," said Agnes Seitz, executive director of Lorne Mt. Community Association. "For one, we don't have real soil. And then we have a very short growing season. We're five to 10 degrees colder than town."

Seitz says she also planted a garden this year, but it's not faring as well as Bartsch's root-heater-equipped plot.

"[Bartsch's plants] are still growing while other gardens are being shut down," said Seitz.

Bartsch's test garden in September 2016. (Submitted by Chris Bartsch)

Although he's still in the "baby stages" of the technology, Bartsch hopes to help the food security situation in the North.

"At the moment, it's small scale," said Jennifer Hall, executive director with the Yukon Agricultural Association. "Whether it can be scaled up to be used in an agricultural context is yet to be seen."

But she says Bartsch often comes to her office to discuss food security.